The theory, which is gaining adherents, remains unproved by actual observation. Surface temperature records date to the late 1800s, but measurements of deep water temperature began only in the 1960s, so there just isn’t enough data to chart the long-term patterns, Xie said.

Scientists have also offered other explanations for the hiatus: lack of sunspot activity, low concentrations of atmospheric water vapor and other marine-related effects. These too remain theories.

In everyday speech, a theory is synonymous to a guess. We say something is “just a theory” to communicate we have, so far, little evidence supporting the guess. Often people use the term to cast doubt on an explanation, that is, to distinguish the explanation from an established fact. In science, however, a theory has a lot of confirming evidence supporting it. A theory in science is just a notch below a law. Because science is always provisional and always open to more data, the number of scientific laws are extremely few. Theories are therefore often our best sets of knowledge. In scientific inquiry, one would likely not use the term “just a theory” to cast doubt on an explanation for why something works the way it does. Researchers hope their findings and interpretations reach the level of a theory.

If these explanations for the hiatus mentioned above are lacking evidence, in the scientific nomenclature they remain hypotheses. They have not reached the level of theory.

Reporters have a difficult time handling the discrepancy between how we use the term theory in everyday speech and how we use it in scientific nomenclature. Most readers will read the word “theory” and assume it carries the definition we use in everyday speech—they won’t assume it has a very specific and technical meaning. Certainly we as a populace can become better educated about scientific inquiry, but we’re not helped when the reporting of science in our major newspapers and magazines doesn’t use the terms accurately.